Field of the Invention
The present invention relates to drug reconstitution devices and, more particularly, to a valve for permitting the mixing of at least two substances within a medical injector or drug cartridge.
Description of Related Art
Certain drugs or medicaments (those terms being used interchangeably herein) are preferably provided in powder or dry form (such as a lyophilized form), and require reconstitution prior to administration. Lyophilized drugs, for example, typically are supplied in a freeze-dried form that needs to be mixed with a diluent to reconstitute the substance into a form that is suitable for injection. Medicaments may also be provided in other dry or powder forms that require reconstitution.
In addition, drugs may be provided as multi-part systems which require mixing prior to administration. For example, one or more liquid (e.g., flowable (slurry or liquid)) components, and/or dry (e.g., powdered or granular) components may be provided in a drug container or delivery device which require mixing prior to administration. Gondatropin and interferon are examples of such multi-component substances which are typically mixed just prior to being administered to a patient.
Prior art devices have been developed that provide a wet component (e.g., liquid) and a dry component (e.g., powder) in separate chambers of a common container with the container being configured to permit the flow of the wet component to the dry component to cause mixing thereof in preparing an administratable solution for injection. The prior devices typically include a bypass channel formed in the container and, as such, the device must be specifically configured for mixing.
Alternatively, prior devices for facilitating the mixing of a wet component and a dry component within a syringe barrel or drug delivery cartridge disclose a valve initially in a closed position which transitions to an open position in response to pressure applied to the valve from the liquid component. Specifically, force from the liquid component overcomes frictional forces between the elements of the valve to open a channel in the valve for the liquid component to pass through. However, these prior valves may fail to open if the frictional engagement between valve elements is too great to be overcome by the fluid force exerted on the valve. In that case, the valve may slip through the barrel instead of opening correctly.
Therefore, there is a need for a reconstitution device which permits mixing of two or more components within a single syringe barrel or drug delivery cartridge and subsequent injection thereof. The cartridge or barrel should not need to be specifically configured for mixing. In addition, the device should have high reliability and, specifically, should not rely on differential frictional forces to transition the valve from a closed to an open position. Finally, the device should have sufficient barrier properties to maintain separation of wet and dry components for long-term storage.